Spatial MALDI-MSI Reveals a Coordinated Vicious Cycle of Oxidative Membrane Damage and Ceramide-Driven Sphingolipid Dysregulation in the Chronically Neuroinflamed Brain

Abstract

BackgroundChronic neuroinflammation is a major driver of cognitive decline, vascular cognitive impairment, and Alzheimers disease. However, the spatial lipidomic alterations underlying neuroinflammatory brain injury remain poorly defined. Oxidative stress and sphingolipid dysregulation have been implicated, but their regional distribution and interplay in the brain are not well characterized. MethodsWe performed positive-ion mode matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) on coronal brain sections from middle-aged spontaneously hypertensive rats (SHR), a model of chronic neuroinflammation, and normotensive Wistar-Kyoto (WKY) controls. Spatial distributions and relative abundances of multiple lipid classes, including phosphatidylcholines (PCs), sphingomyelins (SMs), hexosylceramides (HexCers), ceramides, phosphatidylserines (PSs), phosphatidylinositols (PIs), phosphatidylethanolamines (PEs), phosphatidic acids (PAs), and sulfatides, were mapped and compared between genotypes. Region-of-interest analysis was used to quantify changes across cortex, hippocampus, and white-matter tracts. ResultsSHR brains exhibited a coordinated lipidomic signature characterized by pronounced oxidative stress and membrane remodeling. Oxidized and short-chain PCs were markedly upregulated (up to 11.6-fold), while major structural diacyl PCs were broadly downregulated. Concurrently, sphingolipids were significantly altered, with robust upregulation of SM(d36:1) (7.5-fold) and multiple HexCer species (1.5-1.9-fold), accompanied by accumulation of ceramides. These changes were accompanied by heterogeneous redistribution of PS, PI, and PE species, particularly within the hippocampus. Sulfatide patterns in white-matter tracts were also altered, suggesting myelin remodeling. Region-of-interest analysis confirmed that the most pronounced lipid alterations were concentrated in the hippocampus and white-matter regions. ConclusionsChronic neuroinflammation induces a spatially organized, multi-class lipid remodeling response in the brain, driven by advanced oxidative membrane damage and a shift toward a pro-apoptotic sphingolipid profile. The convergence of these pathways creates a vicious cycle of membrane injury, mitochondrial dysfunction, and sustained neuroinflammation that is especially prominent in the hippocampus and white matter. These spatially resolved findings provide direct evidence that oxidative stress and sphingolipid dysregulation are central, interrelated mechanisms contributing to neurovascular injury and increased risk of cognitive impairment. The study highlights the power of MALDI-MSI to uncover region-specific lipid pathology and identifies potential lipid-based targets for therapeutic intervention in neuroinflammatory brain disease. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=140 SRC="FIGDIR/small/738110v1_ufig1.gif" ALT="Figure 1"> View larger version (47K): org.highwire.dtl.DTLVardef@853af9org.highwire.dtl.DTLVardef@e2d079org.highwire.dtl.DTLVardef@e4e065org.highwire.dtl.DTLVardef@480d80_HPS_FORMAT_FIGEXP M_FIG C_FIG